2000, 22(6):1-4. DOI: 10.11835/j.issn.1674-4764.2000.06.001
Abstract:For the boundary element method of elastodynamics, some properties of matrices are discussed in case of similar boundary elements and the similar boundary element method is presented. In a series of similar boundary elements, when the corresponding matrices of a boundary element are obtained, the ones of other boundary elements in the series can be obtained by proportion. Then the coefficient matrix of the last system of linear algebraic equations can be obtained by the method of superposition. Compared with the general boundary element method, the computing speed can be raised by the similar boundary element method given in this paper.
2000, 22(6):5-6. DOI: 10.11835/j.issn.1674-4764.2000.06.002
Abstract:Green's functions for axisymmetric problems of a piezoelectric half space have been included in a recent paper of Ding et al. (1999). It is found, however, some terms in the solution have been missed there. In this paper, a complete and exact solution is presented.
2000, 22(6):7-11. DOI: 10.11835/j.issn.1674-4764.2000.06.003
Abstract:In this paper, a domain decomposition method for the exterior Helmholtz problem is investigated. The unboundary domain is divided into some non overlapping subdomains. The natural integral operator is used as the artificial boundary conditions on the exterior boundary of the computational domains. The convergence of the algorithm is given in the sense of energy norm. Finally, the discrete problem is discussed and some numerical examples are presented.
2000, 22(6):12-15. DOI: 10.11835/j.issn.1674-4764.2000.06.004
Abstract:应用时域边界元法研究了结构-介质动力相互作用问题。假设摩擦遵守库仑定理。当入射波足够强时界面会出现局部滑移、分离。由于边界上的区域(滑移、分离和粘着)是未知的,所以本问题实际上是个复杂的边界非线性问题。为了确定未知区域,我们应用了一种有效的迭代技术。
2000, 22(6):16-19. DOI: 10.11835/j.issn.1674-4764.2000.06.005
Abstract:In this paper a posteriori error estimates for Galerkin approximation of general operator equations is firstly presented in the framework of Sobolev spaces. Then a practical posteriori error estimates formula for the adaptive boundary element method solving the acoustic scattering problem with a finite plane screen is obtained by triangulations. The mathematical model of this problem is the three dimensional Neumann boundary value problem of Helmholtz equation with finite plane boundary.
KONG Fan zhong , YAO Zhen han , ZHENG Xiao ping
2000, 22(6):20-23. DOI: 10.11835/j.issn.1674-4764.2000.06.006
Abstract:Based on the 2D BEM software THBEM2 developed by the authors' group, which can be applied to simulate the elastic body with randomly distributed circular holes. A scheme of BEM for the simulation of elastic bodies with randomly distributed identical circular inclusions is presented. The workload of the computation is nearly the same as for the corresponding case of circular holes, the numerical examples given show that the scheme is applicable and effective.
2000, 22(6):24-28. DOI: 10.11835/j.issn.1674-4764.2000.06.007
Abstract:This paper presents the numerical implementation of boundary element method incorporated into a non overlapping domain decomposition method for solving the Navier equations of linear elastodynamics problems by Fourier transformation. Several examples are presented.
2000, 22(6):29-33. DOI: 10.11835/j.issn.1674-4764.2000.06.008
Abstract:In this paper, based on multi region boundary element method (BEM), a general procedure to calculate stress intensity factors(SIF) of a 3D mixed mode fatigue surface crack is detailed. A BEM model for a welded T joint is constructed referring to the test specimen. The crack corner points are indirectly estimated to circumvent the treatment of the different crack tip singularity at the corner regions. Numerical results from the welded T joint show that this procedure is reliable.
2000, 22(6):34-36. DOI: 10.11835/j.issn.1674-4764.2000.06.009
Abstract:The boundary element method was used for incompressible viscous fluid flow past a circular cylinder near a plane. The various phases of the flow passing the cylinder are studied numerically with different g/d. The numerical simulation of velocity fields is in good agreement with Davis' theoretical results and Taneda's experiments. In particular, the distributive curves of the surface force and the pressure on the circular cylinder were calculated numerically.
LIU De yi , CHEN Yi ming , SHEN Guang xian
2000, 22(6):37. DOI: 10.11835/j.issn.1674-4764.2000.06.010
Abstract:In this paper the boundary element separation to the elastic contact problems proposed by Kamiya is improved. It gives another optimal penalty factor to accelerate the iteratively saluting procedure, which makes a theoretical foundation for the application of computers' parallel processing method to reduce the calculation time and memory. A practical example is given to confirm the validity of the present method in comparison with Kamiya method.
2000, 22(6):41-44. DOI: 10.11835/j.issn.1674-4764.2000.06.011
Abstract:This paper presents an iteration method of solving non linear boundary integral equations (BIE) of the plane Navier Stokes problem,which each step of the iteration is to solve a linear BIE of nonhomogeneous Stokes problem. Using the quadrature methods of [1],we give a new algorithm with a high order accuracy.The algorithm not only saves work,but also the accuracy can be improved by Richardson extrapolation.
2000, 22(6):45-49. DOI: 10.11835/j.issn.1674-4764.2000.06.012
Abstract:对刚性物体撞水作用下的粘性流场分析,提出了一个Laplace变换-边界元耦合方法。文中基于线性化的二维Navier-Stokes方程,首先利用Lamb变换,在Laplace变换域内将不可压粘性流体的控制方程化为求解相应的势函数和流函数,它们分别满足Laplace方程和Helmholtz方程,采用边界元方法,获得了这两类方程的解答。然后,借助Laplace数值逆变换方法,得到了时间域的解。
SHU Xue dao , SHEN Guang xian , ZHANG Lian dong LI Ming
2000, 22(6):50-53. DOI: 10.11835/j.issn.1674-4764.2000.06.013
Abstract:Mill Roller bearing is made up of internal ring,middle rolls and external ring,which belongs to multi bodies contact problem.So it is rather difficult and complex to analyze load peculiarities of mill roller bearing directly.In this paper,based on three dimensional elastic contact BEM,it is introduced that middle rolling bodies can be described as plate units,placed on the internal ring,therefore the contact problem can be changed from multi bodies to two bodies.As the elastic deformation of plate unit,it can be calculated by Hertz contact formula and is regarded as a gap to be substituted to the total matrix equality,so the three dimensional distribution of load peculiarities of mill roller bearing can be achieved.The calculating model of this method is visualized and simple, and has higher accuracy,therefore it become effective numerical method to design and analyze load peculiarities of mill roller bearing.
2000, 22(6):54-57. DOI: 10.11835/j.issn.1674-4764.2000.06.014
Abstract:引用国内外有关奇异积分方程理论研究的较新成果,讨论了直线段上含任意阶奇异性的奇异积分的数值求积,按照奇点在单元端点和内点两种情况,分别给出了具体的求积公式。最后用本文公式计算了一个有解析结果可资对比的简单实例,表明本文格式精度高 而计算量小。
2000, 22(6):58-61. DOI: 10.11835/j.issn.1674-4764.2000.06.015
Abstract:In this paper, a simpler and direct coupling method, i.e. finite element method coupled with singular solution of infinite plane with a hole, is proposed for the analysis of underground engineering. The numerical example shows that the elastic effectiveness of the infinite plane outside the artificial boundary upon the inside region is exactly expressed.
2000, 22(6):62-66. DOI: 10.11835/j.issn.1674-4764.2000.06.016
Abstract:当用一般的边界元方法解弹性薄板弯曲问题时,域内积分及计算内力时的高阶奇异性是不可避免的。本文应用DRM(Dual Reciprocity Methods)的原理,提出了一种新的解决薄板弯曲问题的边界元方法,并对薄板应力进行了近似计算。所提方法有效地避免了域内积分及高阶奇异性,适合不同的边界条件,具有一定的精度和易用性。
WANG Xiao zhen , ZANG Yue long
2000, 22(6):67-69. DOI: 10.11835/j.issn.1674-4764.2000.06.017
Abstract:Linear boundary element method is used for the analysis of viscous fluid. The velocity components and the fluid mean pressure are taken as unknown functions. The comparison of linear BEM with constant BEM shows that the former presents much better precision and better convergence.
2000, 22(6):70-73. DOI: 10.11835/j.issn.1674-4764.2000.06.018
Abstract:采用对基本随机变量求偏导数的方法建立随机边界积分方程,并具体应用于混凝土重力坝,考虑了坝体材料参数、上游水位和坝基面抗剪断摩擦系数等随机因素。算例分析表明,本文的随机边界元法对诸如混凝土重力坝的大体积建筑物的可靠度分析具有输入数据少,计算结果精度高等优点。
XIANG Zhi hai , CEN Zhang zhi ]
2000, 22(6):74-77. DOI: 10.11835/j.issn.1674-4764.2000.06.019
Abstract:A 3 D boundary element method and dual boundary control technique of material parameter identification were proposed in this paper. The infinite boundary element was used for infinite problem in geomechanics.The computational result shows the validity of the proposed method.
2000, 22(6):78-83. DOI: 10.11835/j.issn.1674-4764.2000.06.020
Abstract:This paper discusses the limitations of extension of classical Hamiltonian Principle to continuous systems, then reviews the new developments of operational theory in functional analysis and variational principles in non equilibrium thermodynamics based on field variation. Complementary dual variational principles including adjoined variational methods and generalized Green function method are bases of finite element analysis and boundary element analysis as well. From the point of view of physics, variational principles of macroscopic non equilibrium thermodynamic can be applied to all continuous mechanical systems. However, they have some limitations in application scope and remain to be developed.
2000, 22(6):84-87. DOI: 10.11835/j.issn.1674-4764.2000.06.021
Abstract:扼要介绍作者研制的包括前后处理的二维边界元法软件THBEM2和三维边界元法软件HBEM3,并通过算例介绍它们在复杂工程问题的线弹性应力分析,以及弹性力学辅助教学等方面的应用。
2000, 22(6):88-91. DOI: 10.11835/j.issn.1674-4764.2000.06.022
Abstract:根据作者提出的处理移动与滚动接触问题边界元法的固定节点-可动节点协调接触方案,给出了带孔洞或裂纹缺陷二维弹性体移动和滚动接触的数值例题,表明该方案的可行性和优越性。
2000, 22(6):92-95. DOI: 10.11835/j.issn.1674-4764.2000.06.023
Abstract:基于微机机群网络,给出了边界元并行计算的若干主要算法,包括单域边界元法求解非对称方程组的并行算法、多子域边界元法求解线性代数方程组的并行算法。给出了边界元并行计算在边界元大规模工程分析中应用的实例。
2000, 22(6):96-99. DOI: 10.11835/j.issn.1674-4764.2000.06.024
Abstract:A dual reciprocity method is proposed for the analysis of fluid sloshing in time domain. With a known initial condition, by each time step, the free surface position is traced and zero stress conditions are imposed on it. If time step is small enough, the boundary conditions are considered almost on the true moving boundary. Further study is to be carried out to verify the precision of this method.
2000, 22(6):100-104. DOI: 10.11835/j.issn.1674-4764.2000.06.025
Abstract:The dynamic response of an underground powerhouse under seismic waves is studied by time domain BEM for anisotropic media. The responses of displacements and stresses are evaluated. The effects of angle and frequency of incident waves and the degree of media anisotropy on dynamic response of the underground structure are analyzed in detail. Some important findings for engineering are obtained.
2000, 22(6):105-107. DOI: 10.11835/j.issn.1674-4764.2000.06.026
Abstract:提出了二维势问题的杂交边界点求解方法。该方法将用于杂交边界元的修正变分原理与移动最小二 乘法结合起来,不但具有边界元法降维的优点,而且是一种真正的无网格方法,即:该方法既不需要插值网格,也不需要积分网格,它的输入数据只是求解域边界上的离散分布的点。数值算例表明:该方法的数值解与解析解吻合得非常好,并且收验速度高。域内未知量的计算不需要象在边界元法和边界点法中做的那样,再一次沿边界积分。
ZHANG Xiao song , ZHAG Ting , ZHAO Yong mao
2000, 22(6):108-111. DOI: 10.11835/j.issn.1674-4764.2000.06.027
Abstract:In this paper,several questions associated with discontinuous boundary elements are discussed.1.The optimum position of collocation point is reevaluated and it is found that accuracy of integrals,especially the nearly singular integrals, is the key factor that influences the accuracy of discontinuous boundary element analysis.2.Discontinuous boundary element is employed for combination of FEM BEM coupling procedure.The patch test, devised by Lu et al,is reconsidered. It is demonstrated that coupling procedure by discontinuous boundary element can achieve results of high accurary.
2000, 22(6):112-116. DOI: 10.11835/j.issn.1674-4764.2000.06.028
Abstract:Based on Melan's theorem, the symmetric Galerkin boundary element method (SGBEM) is used to discretize two dimensional structures and a computational formulation of structural limit analysis is established. The self equilibrium stress field is constructed by linear combination of several basic vectors, which are the stress differences between different iteration steps at the same increment using the traditional elastoplastic incremental method. Then the complex method is used to solve the nonlinear programming directly, so that the lower bound load multiplier of two dimensional structures is obtained. The validation of the present method has been confirmed by some numerical examples.
ZHOU Shen jie , CAO Zhi yuan , SUN Shu xun
2000, 22(6):117-120. DOI: 10.11835/j.issn.1674-4764.2000.06.029
Abstract:Some new developments of boundary contour method have been presented in this paper. The developments include the boundary contour method based on equivalent boundary integral equations, the traction boundary contour method as well as the application of the boundary contour method to crack problems and elastic thin plate bending problems.
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